1. Field of the Invention
The present invention relates in general to headlights of motor vehicles, and more particularly to the headlights of a double beam type which has in a single casing both an upper beam projecting unit and a lower beam projecting unit. More specifically, the present invention is concerned with a double beam type headlight whose lower beam projecting unit includes a light source producing a light, a light reflector reflecting the light from the light source forward, a shading plate shading a part of the reflected light from the reflector and a condensing lens through which the light contoured by the shading plate passes forward.
2. Description of the Prior Art
Usually, headlights of motor vehicles nowadays used are of a double beam type which produces selectively upper and lower beams. The upper beam is the light beam intended for a forward distant illumination which is particularly used when the vehicle is not meeting nor following other vehicles, while the lower beam is the light beam intended for a forward neighbouring illumination particularly used when the vehicle is meeting or following other vehicles.
One of the conventional headlights of the double beam type is schematically illustrated in FIG. 8 of the accompanying drawings, which is generally designated by reference "a". The headlight "a" comprises a lamp body "b" with a front opening and a lens "c" covering the front opening. Within the lamp body "b" there are separately installed an upper beam projecting unit "d" and a lower beam projecting unit "e". The upper beam projecting unit "d" includes a light source "i", and a parabolic reflector "f" having the light source "i" installed at a central part thereof. While, the lower beam projecting unit "e" includes a light source "j", an ellipsoidal reflector "g" having the light source "j" installed at a central part thereof, a condensing lens "h" installed in front of the reflector "g" and a light shading plate "k" arranged between the reflector "g" and the lens "h". The shading plate "k" is placed on a focus of the lens "h". Due to provision of the shading plate "k", the lower light beam projected forward from the condensing lens "h" has a well-contoured cross-sectional pattern. As will be easily understood from the drawing, the double beam headlight of this conventional type can produce desirable upper and lower beams by selectively energizing the light sources "i" and "j" of the beam projecting units "d" and "e".
However, due to its inherency in construction, the headlight of this type has the following drawbacks.
First, because the lower beam projecting unit "e" is substantially entirely housed in the light body "b", it is difficult or at least troublesome to change or adjust the position of the lower beam projecting unit "e". In fact, long use of the headlight tends to make a displacement of the unit "e" from a right position causing ill-directional projection of the lower beam from the unit "e". Of course, in such a case, adjustment of the unit "e" is required.
Second, since the upper and lower beam projecting units "d" and "e" are independently assembled in the lamp body "b", the headlight requires a large number of parts for its production and thus requires a large number of assembling steps. These cause increase in production cost of the headlight.